Piggybacks are nice because of their simplicity and testing. But their disadvantage can be in flexibility. I think they all have limitations in respect to a stand alone solution.

Assembly of the Megasquirt may be easy, but reliability is the key. I'm not sure how robust it will be over time. And usually one thing wrong in your ecu can spell doom for a motor that has a marginally agressive tune.

I personally would go with a more expensive solution with some R&D and a company that's behind it.

I know Trackmasters uses Hondata. And from what I've gathered, it seems like a good solution at fair price. And I like idea of an experienced tuner being local in case I have trouble.